Mammography imaging method using high peak voltage and rhodium or tungsten anodes

Abstract

A method of mammography imaging includes exposing a patient to a peak voltage greater than 29 kVp using X-radiation generating equipment comprising rhodium or tungsten anodes. The film used in this method comprises a cubic grain silver halide emulsion layer on one side of the support and a tabular grain silver halide emulsion layer on the other side. The cubic grain silver halide emulsion layer comprises a combination of first and second spectral sensitizing dyes that provides a combined maximum J-aggregate absorption on the cubic silver halide grains of from about 540 to about 560 nm. The first spectral sensitizing dye is an anionic benzimidazole-benzoxazole carbocyanine, the second spectral sensitizing dye is an anionic oxycarbocyanine. The cubic grain silver halide emulsion layer also includes a mixture of gelatin or a gelatin derivative and a second hydrophilic binder other than gelatin or a gelatin derivative. The cubic silver halide grains comprise from about 1 to about 20 mol % chloride and from about 0.25 to about 1.5 mol % iodide, both based on total silver in the cubic grain emulsion layer, which cubic silver halide grains have an average ECD of from about 0.65 to about 0.8 μm. Moreover, the cubic silver halide grains are doped with a hexacoordination complex compound within part or all of the innermost 95% of the grains. The film can be exposed to provide a black-and-white image having a d(γ)/d(log E) value greater than 5.

1. A method of imaging for mammography comprising exposing a patient to X-radiation at a peak voltage greater than 28 kVp using an X-radiation generating device comprising rhodium or tungsten anodes, and providing a black-and-white image of the exposed patient using an imaging assembly comprising:
 A) a radiographic silver halide film that comprises a support having first and second major surfaces and that is capable of transmitting X-radiation,  
 said radiographic silver halide film having disposed on said first major support surface, one or more hydrophilic colloid layers including at least one cubic grain silver halide emulsion layer, and having disposed on said second major support surface, one or more hydrophilic colloid layers including at least one tabular grain silver halide emulsion layer,  
 wherein said film can be exposed to provide a black-and-white image having a d(γ)/d(log E) value greater than 5, and  
 B) a fluorescent intensifying screen that comprises an inorganic phosphor capable of absorbing X-rays and emitting electromagnetic radiation having a wavelength greater than 300 nm.  
 
     
     
       2. The method of  claim 1  wherein said imaging assembly comprises:
 A) a radiographic silver halide film that has a photographic speed of at least 100 and comprises a support having first and second major surfaces and that is capable of transmitting X-radiation,  
 said radiographic silver halide film having disposed on said first major support surface, one or more hydrophilic colloid layers including at least one cubic grain silver halide emulsion layer, and having disposed on said second major support surface, one or more hydrophilic colloid layers including at least one tabular grain silver halide emulsion layer,  
 wherein said cubic grain silver halide emulsion layer comprises: 
 1) a combination of first and second spectral sensitizing dyes that provides a combined maximum J-aggregate absorption on said cubic silver halide grains of from about 540 to about 560 nm, and  
 wherein said first spectral sensitizing dye is an anionic benzimidazole-benzoxazole carbocyanine, said second spectral sensitizing dye is an anionic oxycarbocyanine, and said first and second spectral sensitizing dyes are present in a molar ratio of from about 0.25:1 to about 4:1,  
 2) a mixture of a first hydrophilic binder that is gelatin or a gelatin derivative and a second hydrophilic binder other than gelatin or a gelatin derivative, wherein the weight ratio of said first hydrophilic binder to said second hydrophilic binder is from about 2:1 to about 5:1, and the level of hardener in said cubic grain silver halide emulsion layer is from about 0.4 to about 1.5 weight % based on the total weight of said first hydrophilic binder in said cubic grain silver halide emulsion layer,  
 3) cubic silver halide grains comprising from about 1 to about 20 mol % chloride and from about 0.25 to about 1.5 mol % iodide, both based on total silver in said cubic grain emulsion layer, which cubic silver halide grains have an average ECD of from about 0.65 to about 0.8 μm, and  
 4) cubic silver halide grains that are doped with a hexacoordination complex compound within part or all of 95% of the innermost volume from the center of said cubic silver halide grains, and  
 
 B) a fluorescent intensifying screen that comprises an inorganic phosphor capable of absorbing X-rays and emitting electromagnetic radiation having a wavelength greater than 300 nm.  
 
     
     
       3. The method of  claim 2  wherein said first spectral sensitizing dye is represented by the following Structure I: 
                 
 
       wherein Z 1  and Z 2  represent the carbon atoms necessary to form a substituted or unsubstituted benzene or naphthalene ring, R 1 , R 2 , and R 3  are independently substituted or unsubstituted alkyl, alkoxy, aryl, or alkenyl groups, X 1   −  is an anion, and n is 1 or 2, and said second spectral sensitizing dye is represented by the following Structure II: 
                 
 
       wherein Z 1  and Z 2  represent the carbon atoms necessary to form a substituted or unsubstituted benzene or naphthalene ring, R 4  and R 5  are independently substituted or unsubstituted alkyl, alkoxy, aryl, or alkenyl groups, R 6  is hydrogen or a substituted or unsubstituted alkyl or phenyl group, X 2   −  is an anion, and n is 1 or 2. 
     
     
       4. The method of  claim 2  wherein the total amount of said combination of said first and second spectral sensitizing dyes is from about 0.25 to about 0.75 mol/mole of silver, and said first and second spectral sensitizing dyes are present in a molar ratio of from about 0.5:1 to about 1.5:1. 
     
     
       5. The method of  claim 2  wherein said combination of said first and second spectral sensitizing dyes provide a combined J-aggregate absorption of from about 545 to about 555 nm when said dyes are absorbed on said cubic silver halide grains. 
     
     
       6. The method of  claim 2  wherein said first spectral sensitizing dye is selected from the following Compounds A-1 to A-7, and the second spectral sensitizing dye is selected from the following Compounds B-1 to B-5: 
                 
                 
                 
 
     
     
       7. The method of  claim 2  wherein said hexacoordination complex compound is present in an amount of from about 1×10 −6  to about 5×10 −4  mole per mole of silver in the silver halide emulsion layer in which it is present. 
     
     
       8. The method of  claim 2  wherein said hexacoordination complex compound is present within the innermost 90% of the volume of said cubic silver halide grains. 
     
     
       9. The method of  claim 2  wherein said hexacoordination complex compound is present within 75 to 80% of the innermost volume from the center of said cubic silver halide grains. 
     
     
       10. The method of  claim 2  wherein said hexacoordination complex compound is represented by the following Structure I:
   [ML 6 ] n    
 
       wherein M is a Group 8 polyvalent transition metal ion, L represents six coordination complex ligands that can be the same or different provided that at least four of the ligands are anionic ligands and at least one of said ligands is more electronegative than any halide ligand, and n is −2, −3, or −4. 
     
     
       11. The method of  claim 10  wherein M is Fe +2 , Ru +2 , Os +2 , Co +3 , Rh +3 , Ir +3 , Pd +3 , or Pt +4 . 
     
     
       12. The method of  claim 10  wherein M is Ru +2 , and at least three of L are cyanide ions. 
     
     
       13. The method of  claim 2  wherein said cubic silver halide grains are composed of from about 10 to about 20 mol % chloride, based on total silver in the emulsion layer. 
     
     
       14. The method of  claim 2  wherein said cubic silver halide grains are composed of from about 0.5 to about 1 mol % iodide, based on total silver in said cubic grain silver halide emulsion layer. 
     
     
       15. The method of  claim 2  wherein the weight ratio of said first hydrophilic binder to said second hydrophilic binder is from about 2.5:1 to about 3.5:1, and the level of said hardener is from about 0.5 to about 1.5 weight % based on the total weight of said first hydrophilic binder in said cubic grain silver halide emulsion layer. 
     
     
       16. The method of  claim 2  wherein said second hydrophilic binder is a dextran or polyacrylamide. 
     
     
       17. A method of imaging for mammography comprising exposing a patient to X-radiation at a peak voltage greater than 28 kVp, said X-radiation generated using rhodium anodes in an X-radiation generating device, and providing a black-and-white image of said exposed patient using an imaging assembly comprising:
 A) a radiographic silver halide film having a photographic speed of at least 100 and comprising a transparent film support having first and second major surfaces and that is capable of transmitting X-radiation,  
 said radiographic silver halide film having disposed on said first major support surface, one or more hydrophilic colloid layers including at least one silver halide emulsion layer, and having disposed on said second major support surface, one or more hydrophilic colloid layers including at least one tabular grain silver halide emulsion layer,  
 said film also comprising a protective overcoat layer disposed on both sides of said support,  
 wherein said cubic grain silver halide emulsion layer comprises: 
 1) a combination of first and second spectral sensitizing dyes that provides a combined maximum J-aggregate absorption of from about 545 to about 555 nm when said dyes are absorbed on the surface of said cubic silver halide grains,  
 
 wherein said first spectral sensitizing dye is the following Dye A-2, and wherein said second spectral sensitizing dye is following Dye B-1, said first and second spectral sensitizing dyes being present in a molar ratio of from about 0.5:1 to about 1.5:1, and the total spectral sensitizing dyes in said film is from about 0.25 to about 0.75 mg/mole of silver, 
                 
 2) a mixture of a first hydrophilic binder that is gelatin or a gelatin derivative and a second hydrophilic binder that is a dextran or polyacrylamide, wherein the weight ratio of said first hydrophilic binder to said second hydrophilic binder is from about 2.5:1 to about 3.5:1 and the level of hardener in said cubic grain silver halide emulsion is from about 0.5 to about 1.5 weight % based on the total weight of said first hydrophilic binder in said cubic grain silver halide emulsion layer,  
 3) cubic silver halide grains comprising from about 10 to about 20 mol % chloride and from about 0.5 to about 1 mol % iodide, both based on total silver in said cubic grain silver halide emulsion layer, which cubic silver halide grains have an average ECD of from about 0.72 to about 0.76 μm, and  
 4) cubic silver halide grains that are doped with a hexacoordination complex compound within 75 to 80% of the innermost volume from the center of said cubic silver halide grains, wherein said hexacoordination complex compound is represented by the following Structure I: 
   [ML 6 ] n    
 
 
 
       wherein M is Fe +2 , Ru +2 , Os +2 , Co +3 , Rh +3 , Ir +3 , Pd +3 , or Pt +4 , L represents six coordination complex ligands that can be the same or different provided that at least three of the ligands are cyanide ions, and n is −2, −3, or −4, and
 B) a single fluorescent intensifying screen that comprises an inorganic phosphor capable of absorbing X-rays and emitting electromagnetic radiation having a wavelength greater than 300 nm, said inorganic phosphor being coated in admixture with a polymeric binder in a phosphor layer disposed on a flexible support and having a protective overcoat disposed over said phosphor layer.  
 
     
     
       18. The method of  claim 2  further comprising processing said radiographic silver halide film, sequentially, with a black-and-white developing composition and a fixing composition, said processing being carried out within 90 seconds, dry-to-dry. 
     
     
       19. The method of  claim 18  being carried out for 60 seconds or less, dry-to-dry.